We are using four cell lines, two MYCN not-amplified and two MYCN amplified cell line that can be grown in a xenograft model. Among other assays we will use the Real-Time Cell Electronic Sensing System (RT-CES system;Acea Biosciences, CA, USA). The most promising targets and the appropriate siRNA will be further evaluated in the two xenograft animal models as outlined above. All positive hits will be further screened in a wider panel of NB Xenografts which will be part of a panel of the Pediatric Preclinical Testing Program (PPTP) which is currently being utilized as a pipeline to screen new drugs and make recommendation for human pediatric phase 1/2 trials (http://ctep.cancer.gov/resources/child.html. We have successfully optimized the high through put siRNA screening using a set of approximately 400 apoptosis related genes and the findings are being prepared for publication.